This invention relates to a control valve for an air pressure bar used in a chair or the like so as to adjust its height or angle, particularly to one having components provided with an annular ridges or grooves to engage with each other to quicken assemblage of the control valve, and the valve body provided with an air passageway for gas to flow through smoothly, and a valve base provided with a stop for stopping and supporting a pin rod from falling off the valve body, enhancing convenience in using it.
Utilization of an air pressure bar able to reciprocate for a distance is already a well-known art for adjusting height or angle of a chair. As shown in FIG. 1, a conventional control valve A for an air pressure device, opens and closes to move a piston rod in an inner and an outer oil tube. In order to form an air passageway for air, a valve body A1 has a center hole A2 for placing a separating ring B and a pin rod C fitting in the separating ring B. The separating ring B at least has an upper flange B2, an air hole B4 in an annular wall B3 communicating with the shaft hole B1, letting the pin rod C movable and functioning to open and close the air flowing passageway with the separating ring B and two gaskets E, E' during reciprocating movement of the pin rod C.
As to this conventional valve A, there is a disadvantage that the pin rod C is movable in the separate ring B, but the ring B is not allowed to move axially in the valve body A1. So an annular gasket D is provided to fit in a lower opening A3 of the center hole A2, and then plural tongues A4 are formed by punching the side edge of the lower opening A3, as shown with dotted lines in FIG. 1 so that the separating ring may be restricted in the center hole A2 of the valve body A. This kind of structure is disadvantageous for making and assemblage.
As to the pin rod C of the conventional valve A, there is also a disadvantage that the pin rod C has a smaller diameter intermediate portion C1 between two larger diameter portions C2 and C3. But the valve body A has at least a side (the opening A3) loaded with high pressured gas, so the pin rod C has to form a small diameter section C1 in the larger diameter portion C3, and fixed with a largest diameter head C4 on the section C3 for preventing the pin rod C from completely moving in the valve body A1 or in the separating ring B. And in pressing or riveting the head C4 on the section C31, the section C1 may be easily bent or disfigured. The larger portions C2, C3 should have a different size from the smaller portion C1 to correspond to the separating ring B and the annular gaskets E, E', and the C1 is commonly 3 mm. Then a comparative large force should be used to operate the control valve A or the pin rod C. Then it is a cause to attract less buyers.
Another disadvantage of the pin rod C is that ramps C5, C5' between the two larger portions C2, C3 and the smaller portion C1 have to be ground two or three times for preventing the annular gasket E from hurt during movement of the pin rod C.